##题目一########
吴=250
wu=251
.w=252
 HU
##题目二########
 A<-c(1:10)
 color<-c('r','g','b','g','b','r','b','r','g','g')
 tapply(A,color,mean)
##题目三#######
 B<-c(11:20)
 C<-c(21:30)
 N<-rbind(color,A,B,C)
 as.data.frame(N)
 ##题目四######
 num=sample(1:50,10,replace = TRUE)
 x=0
 for (i in num) 
{if(i>10)
   {
     x=x+1
   }
 }
 print(num)
 print(x)
 num1=num
 m=i=j=0
 while(i<11)
 {i=i+1
   j=i+1
   while(j<11)
   {
     if(num[i]<num[j])
     {
       m=num[i]
       num[i]=num[j]
       num[j]=m
     }
     j=j+1
   }
 }
 print(num1)
 print(num)